1. Field of the Invention
The present invention generally relates to a monolithic microwave integrated circuit (MMIC), and more particularly to an amplifier having gain and bandpass filter performance for microwave and millimeter-wave wireless communication system.
2. Description of the Related Art
In the microwave and millimeter-wave range, the high integration of MMICs is 3333 increasingly demanded for a variety of applications such as wireless broadband systems, mobile communication systems at 40 GHz and 60 GHz, high-speed millimeter-wave local area networks at 59-62 GHz, and automotive sensors at 24 GHz and 77 GHz. In typical RF transceivers, MMIC chips and off-chip filters are obtained to achieve maximum performance and lowest cost. But the off-chip filters, including band-selection filters and image-rejection filters, are bulky and relatively expensive to hinder the cost reduction. This concept of bandpass amplifier described by Nguyen et al in “A Si bipolar monolithic RF bandpass amplifier,” IEEE J. Solid-State Circuits, vol. 27, no. 1, pp. 123-127, January 1992, has been proposed that the bandpass response is created by the resultant shunt resonator formed by the added inductor with the base-emitter capacitor. They showed an 8-dB gain and 6.4-dB noise figure at 1.5 GHz. A CMOS bandpass amplifier such as described by Wu et al in “The design of a 3-V 900-MHz CMOS bandpass amplifier,” IEEE J. Solid-State Circuits, vol. 32, no. 2, pp. 159-1687, February 1997, was obtained in the 869-893 MHz range by using the positive-feedback Q-enhancement technique. For GPS applications, a 1.6-GHz CMOS bandpass amplifier such as described by Hernandez et al in “A 3 V, 1.6 GHz differential CMOS bandpass amplifier chain for a GPS receiver,” 2000 Topical Meeting on Silicon Monolithic Integrated Circuits in RF Systems Digest, April 2000, pp. 33-37, was designed by incorporating a LC tank at the drain terminal to have bandpass effect. Although the above results show successful single-chip integration of a gain amplifier with a bandpass filter, it is limited below several GHz range. In the millimeter-wave range, a PHEMT bandpass power amplifier such as described by Sasaki et al in, “20-30 GHz broadband MMIC power amplifiers with compact flat gain PHEMT cells,” 2001 IEEE MTT-S Int. Microwave Symp. Dig., June 2001, pp. 1067-1918, had 21-dB gain and 22-dBm PdB over the passband frequency from 20 to 30 GHz. A 4-GHz lowpass amplifier, having the Butterworth or Chebyshev filter approximation was described by Rooney et al in “A filter synthesis technique applied to the design of multistage broadband microwave amplifiers,” 2002 IEEE MTT-S Int. Microwave Symp. Dig., June 2002, pp. 1915-1918.
U.S. Pat. No. 4,984,292 issued to Millen., entitled “Bandpass amplifier and receiver using bandpass amplifier”, discloses that an active bandpass amplifier comprising a single stage operational amplifier, a bridged “T” network single-frequency elimination filter in the negative feedback path of the amplifier and a phase-shift-correcting capacitor associated with the bridged “T” network single-frequency elimination filter to generate a phase shift sufficient to maintain an appropriate feedback such that the amplifier is stable. The bridged “T” network single frequency elimination filter in conjunction with the circuit capacitances and phase shifts in the integrated circuits introduces a phase shift, which would result in the amplifier oscillating when the network is placed in the feedback path and the corrective capacitor generates a corrective phase shift to render the amplifier stable. Such a bandpass amplifier allows high gain and high “Q” and the gain is many times higher than that of a conventional single stage amplifier where gain is typically limited to approximately 5 and the “Q” is limited to about 25. In this case, the bandpass amplifier is capable of gains of greater than 10 and substantially higher “Q”. Such an amplifier is advantageously used in a receiver and in a signaling system. The high gain capability of the receiver is particularly advantageous in a mining environment where the receiver can be used as part of a signalling system. United States Patent Application 20030184378 by Segawa, entitled “Mixer and differential amplifier having bandpass frequency selectivity”, discloses a mixer and a differential amplifier are formed using simple circuit configurations such that the cutoff frequencies thereof can be easily changed. Each of the mixer and the differential amplifier includes an NMOS transistor to which an RF signal is fed, NMOS transistors to which an LO− signal and an LO+ signal are respectively fed from a local oscillator, and two parallel resonant circuits each serving as an output load and including an active inductor, a capacitor, and a resistor. However, it is not yet found on the single-chip bandpass amplifier design in the microwave to millimeter-wave range. According the above problems, the related filed need a new amplifier to overcome the disadvantage of the prior art.